[CodeHealth][ads] Use base::ScopedObservation pt.1

This change replaces the use of local `raw_ptr`s managing observers
manually, for the use of ``base::ScopedObservation`, which is more
idiomatic.

Resolves brave/brave-browser#41607

browser/brave_ads/analytics/p3a/brave_stats_helper.cc

@@ -39,11 +39,7 @@ BraveStatsHelper::BraveStatsHelper()
   profile_manager_observer_.Observe(profile_manager_);
 }
 
-BraveStatsHelper::~BraveStatsHelper() {
-  if (current_profile_) {
-    current_profile_->RemoveObserver(this);
-  }
-}
+BraveStatsHelper::~BraveStatsHelper() = default;
 
 void BraveStatsHelper::RegisterLocalStatePrefs(PrefRegistrySimple* registry) {
   registry->RegisterBooleanPref(prefs::kEnabledForLastProfile, false);
@@ -65,25 +61,23 @@ void BraveStatsHelper::OnProfileAdded(Profile* profile) {
 }
 
 void BraveStatsHelper::OnProfileWillBeDestroyed(Profile* profile) {
-  if (profile != current_profile_) {
+  if (!current_profile_observation_.IsObservingSource(profile)) {
     return;
   }
-  profile->RemoveObserver(this);
-  current_profile_ = nullptr;
+  current_profile_observation_.Reset();
 #if !BUILDFLAG(IS_ANDROID)
   last_used_profile_pref_change_registrar_.RemoveAll();
 #endif
   ads_enabled_pref_change_registrar_.RemoveAll();
 }
 
 void BraveStatsHelper::OnProfileManagerDestroying() {
-  if (current_profile_ != nullptr) {
+  if (current_profile_observation_.IsObserving()) {
 #if !BUILDFLAG(IS_ANDROID)
     last_used_profile_pref_change_registrar_.RemoveAll();
 #endif
     ads_enabled_pref_change_registrar_.RemoveAll();
-    current_profile_->RemoveObserver(this);
-    current_profile_ = nullptr;
+    current_profile_observation_.Reset();
   }
   profile_manager_observer_.Reset();
 }
@@ -109,12 +103,10 @@ PrefService* BraveStatsHelper::GetLastUsedProfilePrefs() {
   if (profile == nullptr || profile->IsOffTheRecord()) {
     return nullptr;
   }
-  if (current_profile_ != nullptr) {
-    current_profile_->RemoveObserver(this);
-    current_profile_ = nullptr;
+  if (current_profile_observation_.IsObserving()) {
+    current_profile_observation_.Reset();
   }
-  current_profile_ = profile;
-  profile->AddObserver(this);
+  current_profile_observation_.Observe(profile);
   return profile->GetPrefs();
 #endif
 }

browser/brave_ads/analytics/p3a/brave_stats_helper.h

@@ -48,7 +48,8 @@ class BraveStatsHelper : public ProfileManagerObserver, public ProfileObserver {
   PrefChangeRegistrar last_used_profile_pref_change_registrar_;
 #endif
   PrefChangeRegistrar ads_enabled_pref_change_registrar_;
-  raw_ptr<Profile> current_profile_ = nullptr;
+  base::ScopedObservation<Profile, ProfileObserver>
+      current_profile_observation_{this};
 
   base::ScopedObservation<ProfileManager, ProfileManagerObserver>
       profile_manager_observer_{this};

browser/ui/views/brave_ads/notification_ad_popup.cc

@@ -100,18 +100,13 @@ NotificationAdPopup::NotificationAdPopup(
 
   display::Screen* screen = display::Screen::GetScreen();
   if (screen) {
-    screen->AddObserver(this);
+    screen_observation_.Observe(screen);
   }
 
   FadeIn();
 }
 
-NotificationAdPopup::~NotificationAdPopup() {
-  display::Screen* screen = display::Screen::GetScreen();
-  if (screen) {
-    screen->RemoveObserver(this);
-  }
-}
+NotificationAdPopup::~NotificationAdPopup() = default;
 
 // static
 void NotificationAdPopup::SetDisableFadeInAnimationForTesting(

browser/ui/views/brave_ads/notification_ad_popup.h

@@ -22,6 +22,10 @@
 
 class Profile;
 
+namespace display {
+class Screen;
+}  // namespace display
+
 namespace gfx {
 class LinearAnimation;
 class Insets;
@@ -157,6 +161,9 @@ class NotificationAdPopup : public views::WidgetDelegateView,
 
   base::ScopedObservation<views::Widget, views::WidgetObserver>
       widget_observation_{this};
+
+  base::ScopedObservation<display::Screen, display::DisplayObserver>
+      screen_observation_{this};
 };
 
 }  // namespace brave_ads

components/brave_ads/browser/ads_service_impl.cc

@@ -194,7 +194,6 @@ AdsServiceImpl::AdsServiceImpl(
       local_state_(local_state),
       url_loader_(std::move(url_loader)),
       channel_name_(channel_name),
-      resource_component_(resource_component),
       history_service_(history_service),
       ads_tooltips_delegate_(std::move(ads_tooltips_delegate)),
       device_id_(std::move(device_id)),
@@ -203,16 +202,17 @@ AdsServiceImpl::AdsServiceImpl(
           {base::MayBlock(), base::TaskPriority::BEST_EFFORT,
            base::TaskShutdownBehavior::BLOCK_SHUTDOWN})),
       ads_service_path_(profile_path.AppendASCII("ads_service")),
-      rewards_service_(rewards_service),
       bat_ads_client_associated_receiver_(this) {
   CHECK(device_id_);
   CHECK(bat_ads_service_factory_);
-  CHECK(rewards_service_);
+  CHECK(rewards_service);
 
   if (!history_service_ || !local_state_) {
     CHECK_IS_TEST();
   }
 
+  rewards_service_observation_.Observe(rewards_service);
+
   if (CanStartBatAdsService()) {
     bat_ads_client_notifier_pending_receiver_ =
         bat_ads_client_notifier_remote_.BindNewPipeAndPassReceiver();
@@ -224,32 +224,22 @@ AdsServiceImpl::AdsServiceImpl(
 
   GetDeviceIdAndMaybeStartBatAdsService();
 
-  if (resource_component_) {
-    resource_component_->AddObserver(this);
+  if (resource_component) {
+    resource_component_observation_.Observe(resource_component);
   } else {
     CHECK_IS_TEST();
   }
-
-  rewards_service_->AddObserver(this);
 }
 
-AdsServiceImpl::~AdsServiceImpl() {
-  if (resource_component_) {
-    resource_component_->RemoveObserver(this);
-  }
-
-  bat_ads_observer_receiver_.reset();
-
-  rewards_service_->RemoveObserver(this);
-}
+AdsServiceImpl::~AdsServiceImpl() = default;
 
 ///////////////////////////////////////////////////////////////////////////////
 
 bool AdsServiceImpl::IsBatAdsServiceBound() const {
   return bat_ads_service_remote_.is_bound();
 }
 
-void AdsServiceImpl::RegisterResourceComponents() const {
+void AdsServiceImpl::RegisterResourceComponents() {
   RegisterResourceComponentsForCurrentCountryCode();
 
   if (UserHasOptedInToNotificationAds()) {
@@ -268,18 +258,19 @@ void AdsServiceImpl::Migrate() {
   }
 }
 
-void AdsServiceImpl::RegisterResourceComponentsForCurrentCountryCode() const {
-  if (resource_component_) {
-    const std::string country_code = brave_l10n::GetCountryCode(local_state_);
-    resource_component_->RegisterComponentForCountryCode(country_code);
+void AdsServiceImpl::RegisterResourceComponentsForCurrentCountryCode() {
+  if (resource_component_observation_.IsObserving()) {
+    resource_component_observation_.GetSource()
+        ->RegisterComponentForCountryCode(
+            brave_l10n::GetCountryCode(local_state_));
   }
 }
 
-void AdsServiceImpl::RegisterResourceComponentsForDefaultLanguageCode() const {
-  if (resource_component_) {
-    const std::string& locale = brave_l10n::GetDefaultLocaleString();
-    const std::string language_code = brave_l10n::GetISOLanguageCode(locale);
-    resource_component_->RegisterComponentForLanguageCode(language_code);
+void AdsServiceImpl::RegisterResourceComponentsForDefaultLanguageCode() {
+  if (resource_component_observation_.IsObserving()) {
+    resource_component_observation_.GetSource()
+        ->RegisterComponentForLanguageCode(brave_l10n::GetISOLanguageCode(
+            brave_l10n::GetDefaultLocaleString()));
   }
 }
 
@@ -434,7 +425,7 @@ void AdsServiceImpl::InitializeDatabase() {
 
 void AdsServiceImpl::InitializeRewardsWallet(
     const size_t current_start_number) {
-  rewards_service_->GetRewardsWallet(
+  rewards_service_observation_.GetSource()->GetRewardsWallet(
       base::BindOnce(&AdsServiceImpl::InitializeRewardsWalletCallback,
                      weak_ptr_factory_.GetWeakPtr(), current_start_number));
 }
@@ -730,7 +721,7 @@ void AdsServiceImpl::NotifyPrefChanged(const std::string& path) const {
 }
 
 void AdsServiceImpl::GetRewardsWallet() {
-  rewards_service_->GetRewardsWallet(
+  rewards_service_observation_.GetSource()->GetRewardsWallet(
       base::BindOnce(&AdsServiceImpl::NotifyRewardsWalletDidUpdate,
                      weak_ptr_factory_.GetWeakPtr()));
 }
@@ -1664,12 +1655,12 @@ void AdsServiceImpl::LoadResourceComponent(
     const std::string& id,
     const int version,
     LoadResourceComponentCallback callback) {
-  if (!resource_component_) {
+  if (!resource_component_observation_.IsObserving()) {
     return std::move(callback).Run({});
   }
 
   std::optional<base::FilePath> file_path =
-      resource_component_->MaybeGetPath(id, version);
+      resource_component_observation_.GetSource()->MaybeGetPath(id, version);
   if (!file_path) {
     return std::move(callback).Run({});
   }
@@ -1811,7 +1802,8 @@ void AdsServiceImpl::Log(const std::string& file,
                          const int32_t line,
                          const int32_t verbose_level,
                          const std::string& message) {
-  rewards_service_->WriteDiagnosticLog(file, line, verbose_level, message);
+  rewards_service_observation_.GetSource()->WriteDiagnosticLog(
+      file, line, verbose_level, message);
 
   const int vlog_level =
       ::logging::GetVlogLevelHelper(file.c_str(), file.length());

components/brave_ads/browser/ads_service_impl.h

@@ -99,9 +99,9 @@ class AdsServiceImpl final : public AdsService,
 
   bool IsBatAdsServiceBound() const;
 
-  void RegisterResourceComponents() const;
-  void RegisterResourceComponentsForCurrentCountryCode() const;
-  void RegisterResourceComponentsForDefaultLanguageCode() const;
+  void RegisterResourceComponents();
+  void RegisterResourceComponentsForCurrentCountryCode();
+  void RegisterResourceComponentsForDefaultLanguageCode();
 
   void Migrate();
 
@@ -449,8 +449,9 @@ class AdsServiceImpl final : public AdsService,
 
   const std::string channel_name_;
 
-  const raw_ptr<brave_ads::ResourceComponent> resource_component_ =
-      nullptr;  // NOT OWNED
+  base::ScopedObservation<brave_ads::ResourceComponent,
+                          ResourceComponentObserver>
+      resource_component_observation_{this};
 
   const raw_ptr<history::HistoryService> history_service_ =
       nullptr;  // NOT OWNED
@@ -465,8 +466,9 @@ class AdsServiceImpl final : public AdsService,
 
   const base::FilePath ads_service_path_;
 
-  const raw_ptr<brave_rewards::RewardsService> rewards_service_{
-      nullptr};  // NOT OWNED
+  base::ScopedObservation<brave_rewards::RewardsService,
+                          brave_rewards::RewardsServiceObserver>
+      rewards_service_observation_{this};
 
   mojo::Receiver<bat_ads::mojom::BatAdsObserver> bat_ads_observer_receiver_{
       this};